Often it is necessary to provide access to the interior of a vessel or shell. This may be accomplished by providing a man-way or door through a wall of the vessel or shell or by removing a section of the shell or vessel to expose the interior thereof. Adding a manway or a door to a vessel increases the cost of fabrication of the vessel and increases the likelihood that the vessel will leak or otherwise permit communication between the interior of the vessel and the environment in which the vessel is located. Similarly, removing a section of the wall of a vessel in order to access the interior of the vessel requires that the opening made through the wall of the vessel be resealed either by replacing the removed section or by applying a patch over the opening. However, neither replacing the removed section nor the application of a patch to the opening through the wall of the vessel is cost effective or an efficient way of closing an opening through the wall of a vessel. Therefore, it would be desirable to provide a structure and method for quickly, easily, and cost effectively gaining access to the interior of a vessel or shell and subsequently closing the shell or vessel in a manner that maintains the integrity of the vessel. It would also be desirable to provide a method for simultaneously producing a series of vessels having varying volumes from a single uniformly sized vessel.